diff --git a/.changeset/khaki-tables-remember.md b/.changeset/khaki-tables-remember.md
new file mode 100644
index 000000000..5ce7873d9
--- /dev/null
+++ b/.changeset/khaki-tables-remember.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Prevent hydration mismatch in streaming SSR
diff --git a/packages/astro/src/runtime/server/render/common.ts b/packages/astro/src/runtime/server/render/common.ts
index b8a998a4a..9274210f5 100644
--- a/packages/astro/src/runtime/server/render/common.ts
+++ b/packages/astro/src/runtime/server/render/common.ts
@@ -69,7 +69,7 @@ export class HTMLParts {
 	}
 	toArrayBuffer() {
 		this.parts.forEach((part, i) => {
-			if (typeof part === 'string') {
+			if(!ArrayBuffer.isView(part)) {
 				this.parts[i] = encoder.encode(String(part));
 			}
 		});